Berkshire Hathaway, the investment fund run by Warren Buffett and Kraft's biggest shareholder, has opposed the food group's plan to issue more shares to fund its bid for Britain's Cadbury. Below is the company's statement:

"Berkshire Hathaway has voted "no" on Kraft's proposal to authorise the issuance of up to 370m shares to facilitate the acquisition of Cadbury.

"Berkshire, taking into account both its own holdings and those of its pension funds, believes that the 138,272,500 Kraft shares it owns – 9.4% of the total outstanding – make it the company's largest shareholder.

"The share-issuance proposal, if enacted, will give Kraft a blank cheque allowing it to change its offer to Cadbury – in any way it wishes – from the transaction presented to shareholders in the proxy statement. And we worry very much that, indeed, there will be an additional change from the revision announced this morning.

"To state the matter simply, a shareholder voting "yes" today is authorising a huge transaction without knowing its cost or the means of payment.

"What we know with certainty, however, is that Kraft stock, at its current price of $27, is a very expensive "currency" to be used in an acquisition. In 2007, in fact, Kraft spent $3.6bn to repurchase shares at about $33 per share, presumably because the directors and management thought the shares to be worth more.

"Does the board now believe those purchases were a mistake and that Kraft's true value is only the current price of $27 per share – and that it is therefore fine to structure a major acquisition based upon that price? Would the directors use stock as merger currency if the price were, say, $20 per share? Surely the true business value of what is given is as important as the true business value of what is received when an acquisition is being evaluated. We hope all shareholders will use this yardstick in deciding how to vote.

"Our understanding is that Kraft must announce its final offer for Cadbury by 19 January. If we conclude at that point that the offer does not destroy value for Kraft shareholders, we will change our vote to "yes." At this time, however, we believe no shareholder should vote "yes" when he can't possibly know what he is voting for."